Stitch length adjusting means for sewing machines



R. E. JOHNSON 2,970,556 STITCH LENGTH ADJUSTING MEANS FOR SEWINGMACHINES Feb. 7, 1961 Filed Feb. 21, 1958 5 I. 2 ERWWMS 5 ma IrinINVENTOR. Ralph E. Johnson BY ATTORNEY Fig WITNESS 44mg;

STITCH LENGTH ADJUSTING MEANS FOR SEWING MACHINES Ralph E. Johnson,Mountainside, N.J., assiguor to The Singer Manufacturing Company,Elizabeth, N.J., a corporation of New Jersey Filed Feb. 21, 1958, Ser.No. 716,696

6 Claims. (Cl. 112-210) This application is a continuation-in-part ofapplication Serial No. 562,096, filed January 30, 1956, which is beingabandoned in favor of the present application.

The present invention relates to a feeding mechanism for sewing machinesand has for a primary object to provide a new and improved stitch lengthadjusting means for the feeding mechanism of a sewing machine.

The usual feeding mechanism of a family type sewing machine includes apivoted block having a guide channel or slideway that cooperates with aslide block on the feed advance. actuating pitman of the feedingmechanism to impart endwise motion to the pitman upon oscillationthereof. The amount of the endwise motion of the pitman determines thefeed advance stroke of the feeding mechanism and, in turn, is determinedby the setting of the pivot block. Manual adjustment of the setting ofthe pivot block is provided by means of a stitch length adjusting leversecured to the pivot block and extending through a slot in the frame ofthe machine, or more commonly, through a slot in a stitch indicatorplate, to Where it is conveniently accessible to the operator. Toindicate the setting of the mechanism, the stitch length adjusting levercooperates with indicia on the frame or stitch indicator plate adjacentto the side edge of the slot.

During normal operation of the machine, it is customary to swing theactuating lever momentarily to the reverse stitching position for backtacking to lock the end of a seam and then to return it to its forwardfeed position. To facilitate returning the leverto the same settingafter back tacking that it had before, the lever is provided with anadjustable stop that cooperates with the stitch indicator plate to limitpivotal movement of the lever to a predetermined setting.

In the usual stitch length adjusting means of family sewing machines itis diflicult to obtain an accurate fine adjustment since movement of thelever about the zero position is so critical. An accurate exceedinglyfine adjustment of the feeding mechanism is required for such :positionof zero feed. The pivot block is frictionally held in its adjustedposition and in view of the mechanics of the connections to the feedingelement, the setting thereof is normally not affected during operationof the machine. However, with a long stitch length, the pivot .block 7is tilted at a maximum relatively to the path of oscillation of theslide block'ltl and there is a corresponding maximum reaction upon thepivot block 7 tending to turn it into alignment with the path ofmovement of the slide block it). This reaction is also directlyproportional to the thickness of the workin that a greater effort isrequired to feed heavy material than to feed light Work. Experience hasshown that. when sewing heavy Patent ice work with a long stitch thesetting of the pivot block may be disturbed. Since a long stitch lengthis normally desired when sewing heavy work, the sewing of such work on afamily sewing machine is difiicult.

In accordance with the above, the present invention is directedspecifically to the provision of a stitch length adjusting means forfamily sewing machines which will afford means for adjustably limitingthe pivotal movement of the stitch length adjusting lever and willclearly indicate the setting of the same and, at the same time, willfacilitate obtaining exceedingly fine adjustments of the feedingmechanism which is required in the very short stitch length settings andwill also hold the stitch length setting when sewing with a long stitchlength on heavy fabric.

Further objects of the invention are to provide a stitch lengthadjusting means having the above advantages but which, at the same time,is simple and economical, easy to operate, dependable, durable andeconomical.

Having in mind the'above and other objects that will be evident from anunderstanding of this disclosure the invention comprises the devices,combinations and arrangements of parts as illustrated in the presentlypreferred embodiment of the invention which is hereinafter set forth insuch detail as to enable those skilled in the art readily to understandthe function, operation, construction and advantages of it when read inconjunction with the accompanying drawings in which:

Fig. 1 is a fragmentary front elevational view of a sewing machineembodying the present invention.

Fig. 2 is a vertical sectional view taken substantially on the line 2-2of Fig. 1.

Fig. 3 is a sectional view taken substantially on the line 3-3 of Fig.2.

Fig. 4 is a view similar to Fig. 2 but illustrating the parts in adifierent position.

Fig. 5 is a sectional view taken substantially on the line 5--5 of Fig.3.

With reference to the drawings, there are illustrated fragmentaryportions of the frame of a sewing machine including a standard 1 and abracket arm 2. The feed ing mechanism of the machine is of a well-knownconstruction comprising a feed-advance pitman 3' arranged vertically inthe standard 1 and having a fork 4 at its upper end. The fork 4 embracesan eccentric 5 on the main shaft 6 which is journaled longitudinally inthe bracket-arm 2. It is the endwise motion of the pitman 3 thatdetermines the feed-advance motion of the feed stroke. Upon oscillationof the pitman 3 by the eccentric 5, endwise motion is imparted to thepitman by an adjustable mechanism including a pivot block 7 pivoted tothe standard 1 by a pivot screw 8 and having a guide channel or slideway9 in which is slidably mounted a slide block it! pivotally secured tothe pitman 3 by a screw 11. The amount of the endwise motion imparted tothe pitman 3 depends upon the orientation of the guide channel 9 withrespect to the center of oscillation of the pitman, which is at itslower end. When the guide channel 9 is tangential to the path ofoscillation of the slide block 10, substantially no endwise motion isimparted to the pitman 3 and there is thus no feed advance motion. Thisis the position of zero feed. When the guide channel 9 is tilted in onedirection, forward motions will be imparted to the pitman 3 and whentilted in the opposite direction, reverse feed motions will be impartedto the pitman 3 the more the guidechannel 9 is tilted, the greater willbe the feed motion.

The pivot block 7 is manually adjusted about its pivot 8 by a stitchlength adjusting lever or rod 12 secured at one in a bore in the pivotblock 7 by a screw 13. The other or free end of the lever 12 extendsthrough an opening 14 in the standard 1, the opening 14 being partiallyclosed by a stitch indicator plate secured to the standard 1 by screws16 and having a vertically elongated slot 17 to accommodate the lever12.

Adjacent to the point of zero or no-feed adjustment of the lever 12there is provided in the plate 15 at one side of the slot 17 a l-shapedconcave depression 18 having side walls or surfaces that are inclinedlengthwise of the slot 17 out of the plane of the plate 15 and convergeat an apex 19 that is at the zero setting of the lever 12.

Extending axially inwardly from the free end of the lever 12 is a slot2t? in which is slidably mounted a planar slide element 21 having alateral finger 22 extending beyond the periphery of the lever 32 at theside adjacent to that edge of the slot 17 having the depression 18. Theslide element 21 has the outer end thereof threaded to cooperate withinternal threads in an axial bore 23 of a thumb nut 24. The nut 24 isjournaled for rotation on the reduced diameter outer end of the lever 12and is held against axial movement between a shoulder 25 on the lever 12and a retaining screw 26 threaded into the end of the lever 12, a washer27 being disposed between the nut 24 and screw 26.

In operation, the lever 12 is adapted to be moved manually along theslot 17 in the usual manner to pivot the block 7 with its channel 9,thereby varying the amount of endwise movement imparted to the pitman 3upon oscillation of the same with the consequent variations in the feedstroke. The finger 22 which is adjusted axially of the lever 12 by meansof the nut 24 will cooperate with the adjacent side of the slot 17outside the depressionl? to form an adjustable stop for limiting. themanipulation of the lever 12 and at the same time, will cooperate withindicia on the plate 15 to indicate the setting of the lever 12. Thus,once a feed setting has been established, which setting will beindicated by cooperation of the finger 22 With indicia provided on theplate 15, the stitching may be reversed for back-tacking by shifting thelever 12 to the other side of the center position and conveniently toits original position. To obtain an accurate fine setting of the feedthe lever 12 is moved along the slot 17 to bring the finger 22 intocooperation with the side walls of the depression 18. The finger 22 isthen movedaxially of the lever 12 by turningthenut 24 and with thefinger cooperating with the side edge of the depression 18 in a cam-likefashion, the lever 12 will be moved a minute amount.

Adjacent to the six-stitches per inch setting of the lever 12, which isthe maximum obtainable stitch length, there is provided. in the plate 15a second concave depression 28 at the same side of the slot 17 as thedepression 18 and in which the finger 22 is adapted to be moved byturning the nut 24. The depression is so formed that when the finger 22is seated therein, the lever 12 is locked against movement thusprecluding the possibility that it will be forced away from this settingduring the operationof the machine.

Numerous, alterations of the structure herein disclosed will suggestthemselves to those skilled in the art. However, it is to be understoodthat the present disclosure relates to a preferred embodiment of myinvention which is for purposes of illustration only and not to beconstrued as a limitation of the invention. All such modi ficationswhich do not depart from the spirit of the invention are intended to beincluded within the scope of theappende'd claims.

Having thus set forth the, nature of this invention, what I claim hereinis:

' l.: In the feeding mechanism of a sewingmachine inof the opening, saidlever having a slot extending axially inwardly from the free endthereof, a slide element slidably mounted in said slot and having afinger extending laterally from said lever into cooperation with saidside edge of the opening and the depression therein, a manuallyrotatable member mounted upon the free end of said lever for rotation,means for confining said rotatable member against axial movement, andoperative connections between said rotatable member and said slideelement for shifting said slide element axially of said lever uponrotation of the rotatable member, said laterally extending finger onsaid slide element being arranged to cooperate with the side edge of theopening adjustably to limit the pivotal movement of the lever andto'cooperate with the inclined surfaces of the depression in a cam-likefashion to effect a fine adjustment of the lever upon movement of theslide element axially of the lever;

2. In the feeding mechanism of a sewing machine having a frame, a blockpivoted to said frame and having a channel for slidably receiving anelement of an oscillating feed advance pitman and for imparting endwisemotion to said pitman upon oscillation thereof, said frame having anopening, a plate for closing said opening and having an elongated slotarranged perpendicular to the pivot axis of said block and a concavedepression at one edge of the slot having surfaces inclined lengthwiseof the slot out of the plane of said plate, and tilting means foradjusting said block about its pivot to vary the endwise motion impartedto the feed-advance pitman upon oscillation thereof, said tilting meanscomprising'a lever secured at one end to said block and having a freeend extending through the slot in said plate whereby the free end ofsaid lever may be manually grasped forshifting said lever lengthwise ofthe slot, said lever having a slot extending inwardly from the free endthereof, a slide element arranged, in the slot in said lever for slidingmovement axially of said lever, said slide element having I a fingerextending laterally from said lever into engagement'with the inclinedsurfaces of the depression in said plate and the adjacent side edge ofthe slot, a manually rotatable member mounted for rotation upon the freeend of said lever, means for confining said rotatable member againstaxial movement, and cooperating threads on said rotatable member andsaid slide element for shifting said .slide element axially of saidlever upon rowith the inclined surfaces of the depression in a camlikefashion to effect a fine adjustment of the lever upon movement of theslide element axially ofthe lever.

3. In the feeding mechanism of a sewing machine having a frame, a blockpivoted to said frame and having a channel for slidably receiving anelement of an oscillating feed advance pitman and for imparting endwisemotion to said pitman upon oscillation thereof, said frame having anopening, a plate for closing said opening and having an enlongatedslotarranged perpendicular to the pivot axis of said block, and tiltingmeans for adjusting said block about its pivot to vary the endwisemotion imparted to the feed-advance pitman upon oscillation thereof,said tilting means comprising a'lever secured at one end to said blockand having a free end extending through the slotin. said plate wherebythe free end of-said lever may be manually grasped'for shifting saidlever lengthwise of: the slot, said lever having a slot extending wardlyfrom the free end thereof, a slide element arranged in, the slot in saidlever for sliding movement axially of said lever; said slide elementhaving a finger extending laterally from said lever into engagement withthe adjacent side edge of' the slot, a manually rotatable member mountedfor rotation upon the free end-of said lever, means for confining saidrotatable member against axial movement, and cooperating threads on saidrotatable member and said slide element for shifting said slide elementaxially of said lever upon rotation of said rotatable member, saidlaterally extending finger on said slide element being arranged tocooperate with the side edge of the slot in the plate adjustably tolimit the pivotal movement of the lever.

4. In the feeding mechanism of a sewing machine including a frame havingan opening and a stitch length adjustment lever having a free endextending through said opening to where it is conveniently accessible tothe operator, said lever being adapted to adjust the feeding mechanismbetween zero and a maximum stitch length upon pivotal movement thereof,a stitch indicator plate disposed over said opening and having a slotthrough which said lever extends, said slot having a side edge arrangedparallel and closely adjacent to the path of travel of said adjustinglever, said plate having a first and a second concave depression in theside edge thereof, said first depression being disposed adjacent to thepoint on said plate corresponding to the zero stitch length setting ofsaid lever and defining surfaces inclined lengthwise of said side edge,said second depression being disposed adjacent to the point on saidplate corresponding to the maximum stitch length setting of said lever,said lever having a slot extending axially inwardly from the freeendthereof, a slide element mounted in said slot and having a fingerextending laterally from said lever into cooperation with said side edgeof the opening and the depressions therein, a manually rotatable membermounted upon the free end of said lever for rotation, means forconfining said rotatable member against axial movement, and operativeconnections between said rotatable memher and said slide element forshifting said slide element axially of said lever upon rotation of saidrotatable memher, said laterally extending finger being adapted tocooperate with the side edge of the opening adjustably to limit thepivotal movement of the lever, to cooperate with the inclined surfacesof the first depression in a cam-like fashion to effect a fineadjustment of the lever upon movement of the slide element axially ofsaid lever, and to cooperate with the second depression to lock saidlever against pivotal movement.

5. Stitch length adjusting means for sewing machines comprising a stitchindicator plate having an elongated slot, a stitch length adjustinglever extending through the slot andadapted to be shifted along the slotin opposite directions from a center position defined by the zero stitchlength setting of said lever to provide for forward and reverse settingsand to vary the setting from zero to a maximum as said lever is movedaway from said center position, said plate having a side edge adjacentto said slot arranged parallel and closely adjacent to the path oftravel of said lever, a finger extending laterally from said lever forengaging said side edge, and means for manually shifting said fingeraxially of said lever, said plate at the portion adjacent to said sideedge being substantially planar with a concave V-shaped depressionformed therein in the area immediately adjacent to the zero stitchlength setting of said lever with the base of said depression at theZero stitch length setting and presenting inclined surfaces lengthwiseof the slot, said laterally extending finger being arrangedto cooperatewith the planar portion of said plate adjacent to said side edge in therange of normal stitch lengths and with the inclined edges of saiddepression in the range of fine stitch lengths adjustably to limit thepivotal movement of the lever and to cooperate with the inclinedsurfaces of the depression in a cam-like fashion to eifect a fineadjustment of the lever upon movement of the finger axially of thelever.

6. In the feeding mechanism of a sewing machine having a frame, a blockpivoted to said frame and having a channel for slidably receiving anelement of an oscillating feed advance pitman and for imparting endwisemotion to said pitman upon oscillation thereof relatively to said blockwith the endwise motion imparted to said pitman being variable betweenzero and a maximum upon pivotal movement of said block, said framehaving an opening, a plate, for closing said opening and having anelongated slot including a side edge arranged perpendicular to the pivotaxis of said block, tilting means for adjusting said block about itspivot axis comprising a lever secured at one end to said block andhaving a free end extending through the slot in said plate whereby thefree end of said lever may be manually grasped for shifting said leverlengthwise of said slot, a finger slidably mounted on the free end ofsaid lever for movement axially thereof and extending laterally fromsaid lever for cooperating with the side edge of said slot to limit thepivotal movement of said lever, and means for moving said finger axiallyof said lever, said plate having a concave depression in said side edgeof the slot at the point engaged by said finger when said lever is movedadjacent to the maximum stitch length setting, and in which said fingeris adapted to be seated to lock said lever against pivotal movement.

References Cited in the file of this patent UNITED STATES PATENTS1,397,071 Becker Nov. 15, 1921 2,525,578 Austlid Oct. 10, 1950 FOREIGNPATENTS 634,711 Germany Sept. 2, 1936 634,748 Germany Sept. 2, 1936697,934 Germany Oct. 28, 1940 732,820 Germany Mar. 12, 1943

